1. Field of the Invention
The present invention relates to a gas compressor.
2. Description of Related Art
Japanese Patent Application Laid-Open No. 2006-144636 (Patent Document 1) discloses a gas compressor.
As shown in FIG. 5, this gas compressor 201 is a vane type compressor. In the vane type compressor 201, a check valve 205 is provided on a gas suction path 203 through which suctioned refrigerant flows. The check valve 205 prevents gas from flowing backward.
As shown in FIG. 5 or 6, the check valve 205 includes a cylinder 209, a valving element 211, a coil spring 213 and so on. The tubular cylinder 209 is opened toward the gas suction path 203 through a stopper 207 (valve seat). The valving element 211 is accommodated within the cylinder 209 movably. The coil spring 213 urges the valving element 213 toward the stopper 207. The valving element 211 moves within the cylinder 209 according to balance among a restoring force of the coil spring 213, an outside pressure and a pressure in the gas suction path 203. In suction process, the coil spring 213 compressed and the valving element 211 is set back while suctioned refrigerant flows through the gas suction path 203. In compression process, the coil spring 213 makes the valving element 211 contacted with the stopper 207 to close the gas flow path 203 and thereby leakage of refrigerant and oil is prevented.
In addition, the valving element 211 is urged toward the stopper 207 when refrigerant pressure becomes large at a bottom 215 of the cylinder 209. As a result, the above-mentioned balance becomes lost and thereby it may occur that the check valve 201 cannot function normally.
Therefore, refrigerant release paths 217 and 219 are provided in a casing 221 to return the refrigerant stagnating at the bottom 215 to the gas suction path 203. The refrigerant release paths 217 and 219 shown in FIG. 5 are different from those shown in FIG. 6 in their machining order. Since one of the refrigerant release paths 217 and 219 needs to be formed from an outside of the casing 211 in any cases shown in FIGS. 5 and 6, a plug 223 and a gasket 225 is used to prevent leakage of refrigerant and oil.